1. Field of the Invention
The present invention relates to a control apparatus for an internal combustion engine, and particularly, to a control apparatus for an internal combustion engine having a reverse rotation detecting function of the internal combustion engine.
2. Description of Related Art
When ignition is made before a compression top dead center in a case where the rotational speed of a crankshaft is insufficient at the startup (cranking) of an internal combustion engine by manual operation, a phenomenon, so-called rebounding of kick pedal in which the crankshaft makes reverse rotation and a reverse rotation load is applied to manual starting operation devices (e.g., kick arm) may occur.
As techniques for preventing such rebounding of kick pedal, techniques mentioned in the following (1) and (2) are conventionally known.    (1) As disclosed in Japanese Patent No. 2780257, in an ignition device that performs ignition output according to an output voltage signal of a crank angle position detecting timing sensor (crank sensor), when the ignition device detects that an output voltage signal of a predetermined phase of the crank sensor does not coincide with an output voltage of one of the predetermined phases of a magnet-type AC generator that rotates in synchronization with a crankshaft, ignition output is stopped.    (2) As disclosed in Japanese Patent No. 3125587, in an ignition device that has a power source coil exclusive for ignition (so-called exciter coil) that is packaged in a magnet-type AC generator, the power source coil outputs an alternating voltage with a plurality of cycles per one revolution in synchronization with the rotation of a crankshaft, the ignition device causes ignition output to be stopped according to an output voltage of an exciter coil with a predetermined phase.
In the above conventional techniques, when any noises are generated in output voltage signals of the magnet-type AC generator that is used for detection of reverse rotation (including the exciter coil), the reverse rotation may be erroneously detected only by detecting the predetermined phases of these signals once. Furthermore, startup of an internal combustion engine may be disabled, or there is concern that an engine stall is caused if the engine is under operation.
Furthermore, when an abnormality, such as a case where the magnet-type AC generator or the exciter coil is short-circuited from other power sources (e.g., a multi-phase generator or a battery), the reverse rotation cannot be detected, and rebounding of kick pedal cannot be prevented.
Meanwhile, as the techniques for detecting the reverse rotation of an internal combustion engine, techniques mentioned in the following (3) to (5) are known.    (3) As disclosed in Japanese Patent No. 2780257, when an ignition device detects that a signal of a predetermined phase of a crank sensor does not match to an output voltage of one of the predetermined phases of an AC generator, the ignition device determines reversal rotation, and ignition output is stopped.    (4) As disclosed in Japanese Unexamined Patent Application, First Publication No. S62-75075, a counter-electromotive force that is generated by a normally meshing-type starter motor is detected at the time of reverse rotation, and a spark is prevented.    (5) As disclosed in Japanese Patent No. 3375679, two projections including a reference projection and an auxiliary projection is provided in a timing rotor that rotates in synchronization with a crankshaft, and reverse rotation is detected based on the detection timing of these projections.
Furthermore, generally, in order to release a reverse rotation detection result (that is, ignition prohibition), an engine stall (crank rotation stop) is necessary.
As disclosed in Japanese Unexamined Patent Application, First Publication No. 2005-220866, a technique for releasing ignition prohibition is known. Specifically, in the case where, after reverse rotation is detected by the technique similar to the above-described (3), when negative pulses of the AC generator have been detected greater than or equal to 4 times (equivalent to ½ rotation), or when a predetermined time has elapsed from the reverse rotation detection, ignition prohibition is released.
In a case where an engine stall is adopted as a release condition of the above-described reverse rotation detection result, when a starter motor or a manual startup device (e.g., kick pedal) is operated continuously, startup may be disabled without releasing the reverse rotation detection result.
Furthermore, when the pulse number of the AC generator, crank signal input, and elapsed time are adopted as release conditions of the reverse rotation detection result, since engine forward rotation is not detected, there is concern that the reverse rotation detection result (ignition output permission) is released at the time of reverse rotation. In that case, parts (e.g., starter idle gears, and an engine body) constituting a startup drive system may be damaged.